(1) Field of the Invention
This invention relates to methods of removing, in time of manufacture, unnecessary resist patterns from surfaces of various micro-fabricated articles such as semiconductor substrates, printed circuit boards, masks and lead frames.
(2) Description of the Related Art
When manufacturing a semiconductor device, for example, a resist solution is applied to a semiconductor substrate such as a silicon wafer. A predetermined image (resist pattern) is formed thereon through a usual photographic process. The resist pattern is used as a mask in various processes including ion injection, etching and doping. Subsequently, the resist pattern no longer needed is removed to form a predetermined circuit. Then, the resist solution is applied again to form a next circuit. This cycle is repeated. Also where circuits are formed on various substrates, unnecessary resist patterns are removed after image formation. Generally, unnecessary resist patterns are removed using an asher (ashing device) or a solvent (releasing solution). When the asher is used, the operation may be time-consuming, and impurity ions in the resist pattern could remain on the surfaces of wafers. Use of the solvent poses the problem of impairing work environment.
A method of removing unnecessary resist patterns with adhesive tape has been proposed recently as disclosed in U.S. Pat. No. 5,759,336, for example. With this method, the adhesive tape is applied to a surface of a resist pattern on a wafer surface, and this adhesive tape is separated along with the resist pattern from the wafer surface.
The proposed method of removing resist patterns with adhesive tape avoids the inconveniences encountered in the conventional practice of resist pattern removal using an asher or a solvent. However, the proposed method has the following drawback. A resist pattern on an article such as a semiconductor substrate is extremely small and has only a small area of contact with an adhesive on the adhesive tape applied. On the other hand, the resist pattern adheres to the article with great bonding strength. The resist pattern may remain on the article without being separated therefrom as sticking to the adhesive tape. It is thus difficult to remove the resist pattern from the article completely.